1. Field of the Invention
Embodiments of the present invention are directed to an x-ray digital image detector comprising a scintillator screen, a wide-angle lens, a transparent x-ray shield, and an image sensor. The present invention also includes a software correction algorithm to rectify imaging distortion and a light intensity compensation algorithm to compensate for solid angle changes in the received light.
2. Description of the Related Art
Early x-ray digital camera systems utilized a lens/mirror assembly to project an x-ray scintillator screen image onto a commercial charge-coupled device (CCD) sensor that captured the image. However, because of the small dimensions of a typical CCD sensor compared to large scintillator screens, substantial demagnification and light loss meant that such a digital camera system was not a feasible choice in digital radiography. At present, most commercial digital radiography systems use flat panel detectors, comprising either an amorphous silicon TFT panel coupled with a scintillator layer, or an amorphous selenium TFT panel. Only a few systems used a lens/mirror type x-ray camera detector with competitive imaging quality.
While amorphous silicon TFT panels coupled with scintillator layers promise good resolution and high sensitivity, the high manufacturing cost hinders the quick adoption of such an approach to digital radiography. In this invention, a simple camera-based detector system is designed to take advantage of current advances in CCD/CMOS digital image sensor technology, as well as improvements in scintillator screen technology and optical lens designs.
What is needed in the art is an optical assembly that projects x-ray images formed on a scintillator screen directly onto a much smaller image sensor via a fisheye or super-wide-angle lens, while protecting the image sensor with transparent x-ray shielding, and correcting any imaging distortion using a software rectification algorithm. Such a detector would greatly simplify the design complexity of a camera-based x-ray detector, thus substantially reducing manufacturing costs, while maintaining a comparable imaging quality and efficiency.